Carburetor



July 30, 1935. M. MALLQRY 2,009937 CARBURETOR Filed July 3, 1954 2Sheets-Sheet l 'iili -f Jmy 50, E935, M, MALLORY 2,609,937

CARBURETOR Filed July 3, 1934 2 SheetS-Shee 2 @t 'PI ml [Ily MI BQ S I,|III1 r IIHII'I "HH )M1 Ill l. l ui'f IIIIH 2 'P i| @s n l g .1 NIH: I'M a P US Home Patented July 30, 1935 UNITED 4STATES PATENT OFFICE 8Claims.

the present instance, by controlling the flow of air into and throughthe chamber within which the primary mixture takes place. The inventionalso is easily adapted to thermostatic regulation of the mixture untilthe engine isWarmed up.

The means by which the above objects are attained will be moreparticularly described in connection with the accompanying drawings, inwhich,-

Flgure 1 is a central vertical section taken through the air intakepassageway and the float chamber of a carburetor constructed accordingto the invention.

Figure 2 is a section taken on the line Figure 1.

Figure 3 is a view similar to Figure 1, illustrating a modification.

Figure 4 is a section taken on the line 4--4 of Figure 3.

The invention is illustrated in connection with a down draft carburetorhaving a main fuel passageway IIJ provided with an air intake II andwith an outlet I2, within which is a throttle valve I3. A float chamberI4 is supplied with fuel through a pipe I5 past a valve I6 which iscontrolled by the usual float II, so as to maintain the fuel at aconstant level within the chamber 40 I4. From the chamber I4, fuel flowsthrough a passageway I8 and main fuel restriction I9 into a well 20. y

A bar or bridge 2| extends across the passageway I and has a mixingchamber in the form 45 of a tube 22 secured thereto. This tube orchamber has air bleed from the well 20, wardly at the center of When theengine is idling, fuel is supplied from the well 20 through idling tube26, idling fuel restriction 21 and passageway 28, where air is mixedwith the fuel. The fuel mixture then issues through the idle outletrestriction 29 tothe fuel intake passageway on the engine side of thethrottle valve I3. A-ir is admitted to the passageway 28 through airinlet 30 and the amount of air thus admitted is adjusted by a screw 3|.

Air flow through the passageway I0 is adapted to be restricted by valves32 which. in the present instance, are secured to pivot pins 33, eachand an outlet 25 opening downthe passageway I0.

holes 23, a fuel inlet 24 leading I Cl. 261-46) of which has a springcontrolled crank or eccentric 34, outside of the carburetor casing, tourge the valve toward closed position.

In the construction shown in Figures 1 and 2, a venturi 35 is locatedabove the valves 32 and the bleed holes 23 are located substantially atthe choke of the venturi, so that as the air flow through the venturiincreases, due to a wider opening of the throttle valve, the ratio ofair to fuel in the mixing tube 22 is decreased. A sleeve 36 is slidablymounted on the tube 22 and its movement is controlled by a link 3lconnecting it to a wrist pin 38 on a crank disk 39, which is secured toa shaft 46 mounted transversely to the air intake II. A crank 4I,secured to the shaft 40, is connected by a link 42 to a thermostat 43.At low temperatures, the thermostat moves the sleeve 36 upwardly tocover the holes 23. At the same time, a flange 44 on the sleeve 36engages crank arms 45 on the hubs of the re`- spective valves 32 andimposes an additional load tending to close them, thereby insuring arich mixture. As the temperature rises, the thermostat lowers the sleeve36, progressively uncovering the holes 23 and releasing the valve 32, sothat the mixture is ultimately regulated by the air ow controlled by thethrottle valve and the engine suction.

In the construction shown in Figures 3 and 4, the venturi is omitted andthe valves 32 are connected by links 46 to a sleeve 4l whichprogressively covers the holes'23 to mechanically cut down the ratio ofair to fuel supplied to the mixing tube 22, instead of effecting thisresult by the kinetic suction of themain air flow, as in theconstruction shown in Figures 1 and 2. The plunger 48 inside of the tube22 and connected to the link 31, as shown in Figures 3 and 4, serveslthe same purpose as the sleeve 36 in Figures 1 and 2, in covering oruncovering the holes 23 in response to changes in temperature.

In air valve carburetors as heretofore constructed, the fuel supply isusually regulated by a metering pin in the main fuel orifice, but withsuch a construction, considerable difficulty is encountered because ofthe extreme accuracy required in its manufacture and because of itsinability to hold its calibration under normal service conditions. Inaccordance with the present invention, the metering is effected byregulating r the flow of air through the holes 23, either by mechanicalmeans connectedl with the restrictive valves 32 or by the kineticsuction of the main air flow through the venturi 35. Regulation by thismethod requires far less precision than regulation by direct metering ofthe fuel stream, because the average mixture ratio is approximatelysixteen parts of air to one of fuel.

In the operation of this invention, no metering pin is required. Theamount of fuel supplied to the engine is determined by the rate of airowthrough the bleed holes 23 into the primary mixing tube 22.

In the construction shown in Figures 1 and 2, when the engine isoperating at low speed, the restriction of the valves 32 causes arelatively large ow of airthrough the holes 23, which reduces thesuction through the fuel inlet 24, thereby reducing the amount of fuelsupplied to the engine. As the engine speed increases, the valves 32open wider in`response to greater suction. However, regardless of theslightly increased suction on the outlet 25, less air enters the inlets23 than at low speed, due to the increased suction through the venturi.

In the modification shown in Figures 3 and 4, there is no venturi, but asimilar regulation of the amount of air flowing into the mixing tube 22is positively effected by mechanical means, rather than suction of themain air ilow. In other words, as the restrictive valves 32 open, theair bleed holes 23 are progressively closed by the sleeve 4l, which hasdirect link connections with the valves.

In both forms of the invention herein shown, the thermostat 43 and itsconnections closev the bleed holes 23 when the engine is cold andprogressvely open them as the engine warms up.

While the construction of the primary mixing tube is particularly welladapted to be combined with thermostatic regulation, the latter may, ofcourse, be omitted if desired. It will also be apparent that the meansfor regulating the fuel flow in response to variations in the flow ofthe main air stream may be considerably modified without departing fromthe scope of the appended claims. I claim:

l. In a carburetor, the combination of a main air passageway, an airvalve therein, yieldable means tending to close said valve, a primarymixing tube with one end closed andwith theother end opening into saidpassageway on the engine side of said air valve. said tube having an airinlet and a fuel inlet, a sleeve on said tube, and means the air flowthrough said passageway is increased,

and thermostatic means independent of the air flow for reducing thesupply of air to said mixing chamber at low temperatures.

3. In a carburetor, the combination of a main -aiipassageway, an airvalve therein, yieldable means tending to close said valve, a primarymixing chamber havingl an air inlet from said passageway onthe-atmospheric side of saidair. valve and having also a fuel inletopening of constant size, an outlet from said chamber to said passagewayon the engine side of said air valve, a throttle valve on the engineside of said outlet, means for progressively reducing the ratio of airto fuel supplied to said chamber as the throttle valve is opened, andthermostatic means effective independently of said air valve to reducesaid ratio at low temperatures.

4. In a carburetor, the combination of a main air passageway, an airvalve therein, yieldable means tending to close said valve, a venturi insaid passageway on the atmospheric side of said air valve, a primarymixing ch'amber within said passageway having an air-inlet therefrom atthe choke of the venturi and having also a fuel inlet opening ofconstant size, a throttle valve in said passageway on the engine side ofsaid air valve, an outlet from said chamber into said passageway betweenthe air valve and the throttle valve, whereby the suction through theventuri progressively reduces the ratio of air to fuel supplied to saidchamber as the throttle valve is opened, and thermostatic means operableindependently of the air suction to reduce said ratio at lowtemperatures.

5. In a carburetor, the combination of a mainair passageway, an` airvalve therein, yieldable means tending to close said valve, a primarymixing chamber having a fuel inlet opening of constant size and an airinlet, an outlet from said chamber to said passageway on the engine sideof said air valve, means for progressively closing the air inlet to saidchamber as said air valve is opened, and thermostatic means to closesaid air inlet, independently of said air valve, at low temperatures.

6. In a carburetor, the combination of a main air passageway, an airvalve therein, yieldable means tending to close said valve, a primarymixing tube with one end closed and with the other end opening into saidpassageway on the engine side of said air valve, said tube having a fuelinlet opening of constant size and an air inlet, a sleeve on said tube,means for moving said sleeve to progressivelycover said air inlet assaid air valve is opened, and thermostatic means independent of saidsleeve to restrict said air inlet at low tem-- peratures.

7. In a carburetor, the combination of a main air passageway, an airvalve therein adapted to be opened by the air flow, yieldable meanstending to close said valve, a primary mixing chamber having an airinlet and a fuel inlet opening of constant size and having an outletinto said passageway, means for utilizing the main air ilow to reducethe ratio of air to fuel supplied to'said primary mixing chamber as themain air flow increases, and thermostatic means operable at lowtemperatures to cut down the air supply to said chamber regardless ofthe rate of the main air flow.

8. In a carburetor, the combination of a main air passageway, an airvalve therein adapted to be opened by the air flow, yieldable meanstending to close said valve, a primary mixing chamber having an airinlet and av fuel inlet and having an outlet into said passageway, meansfor utilizing the main air flow to reduce the ratio of air to fuelsupplied to said primary mixing chamber as the main air flow increases,thermostatic means operable at low temperatures to cut down the airsupply to said chamber regardless of the rate of the main air flow, andmeans actuated by the thermostatically controlled meansl to positivelyclose said air valve as the air supply to the primary mixingchamber isthus cut down.

MARION MALLORY.

